Such an articulated steering load-carrying vehicle is previously known from WO2009/108089 A1. This document relates to an articulated steering load-carrying vehicle of hybrid type, wherein a front mounted combustion engine over a generator powers a front wheel pair as well as two driven wheel pairs arranged on the rear portion, wherein these two wheel pairs are arranged in a bogie configuration.
Through this construction the previously known vehicle on the one hand has a greater load-carrying ability, on the other hand enhanced propulsive ability in relation to an articulated steering load-carrying vehicle with one driven front wheel pair and with only one driven wheel pair on the rear portion.
The load-carrying vehicle according to WO2009/108089 A1 is, however, limited in respect of use and driveability.
As examples of background art for increasing transport speed during driving uphill with high load are: increased power in the driving system, i.e. increased engine power, increased capacity of the transmission and driveline. The previously known solutions give, however, increased vehicle dimensions and in particular wheel dimensions. Besides additional costs for driving gear as well as chassis construction of the vehicle and wheel costs, hereby the need increases for increased dimensions of tunnels, wherein a vehicle is to be driven, with all the economic consequences this results in, such as requirements of increased costs for tunnel driving.
SE 465 771, DE 10005527 and SE 509 847 are further examples of documents representing the background art.
Aim and Most Important Features of the Invention
An aim of the present invention is to provide an economically producible articulated steering load-carrying vehicle of the kind indicated above, which allows good driveability and flexibility during high loading capacity.
This aim is obtained in a load-carrying vehicle as above in that the second wheel pair normally being positioned most rearwardly on the rear portion being steeringly connected to the rear portion seen in regard of steering, that the second wheel pair is electrically motor driven over electrical motor means, that a second power engine is arranged to power supply said electric motor means over an electric generator, and that the second power engine and the associated electric generator are arranged in the rear portion. With “as regards steering” is herein intended steering for the purpose of turning of the vehicle.
Hereby great advantages are obtained in particular for an articulated steering load-carrying vehicle intended for use in mines below ground, when it is very important to be able to drive as smoothly as possible with a load-carrying vehicle with as high load capacity as possible in as narrow tunnels and galleries as possible.
In particular, the invention is advantageous for driving uphill, since a vehicle according to the invention can be driven in steeper uphill slopes. This results in that tunnels can be planed with a higher degree of inclination, which is a great economic advantage, since hereby totally shorter tunnels can be planed for a mine or an underground building project.
During mining, tunnel driving for transport tunnels is a necessary evil, as seen economically, to the extent that there is a desire to have as short tunnels with as narrow dimensions as possible in order to avoid the costs brought about for driving and scaling out and reinforcing tunnels of greater dimensions. The smaller dimensions of the tunnels, the lower the extraction costs for material obtained in the mine. For that reason there is an aim to provide longer vehicles, that have good drivability and in particular ability of be driven in curves in tunnels having as small dimensions as possible. When providing longer load-carrying vehicles, there are, however, problems with dimensions of everything from wheel to driving engine.
By providing two driven wheel pairs on the rear portion, wherein a second wheel pair is also, in regard to steering, steeringly connected to the rear portion, the wheels can be used more optimally and wear because of skidding tires on bogies not being steered can be avoided, problems that the vehicle according to WO2009/108089 A1 suffers from. With “skidding tires” is here intended tires that are not rolling ideally against the ground because of its wheel axis not being directed against the turning centre of the vehicle, and which therefore experience a certain “skidding” against the ground also during normal turning. The working life of the load-carrying vehicle as well as in particular the tires can thereby be considerably extended in regard of a vehicle according to the invention.
By further a second power engine being arranged over an electric generator to power supply the electric motor means which drives the wheels of the second wheel pair, the load capacity and the transport speed in uphill slopes can be considerably enhanced in spaces were width and height of the tunnel are limited in that the first driving motor and associated driveline components do not have to be dimensioned for powering the wheels in this second wheel pair. Hereby the ratio between loading capacity and tire dimension of the vehicle is enhanced and the space requirements are reduced.
By the second power engine and the associated electric generator being arranged in the rear portion, advantages are obtained as regards installation and space.
Said second power engine can be arranged to be engaged as required such as when driving with load uphill, wherein in such cases all wheel pairs of the vehicle are driven. During drive modes where the power requirement is less, the second power engine can be disconnected and propulsion take place over the first power engine which is the main engine of the vehicle.
In a particular aspect, the first wheel pair is electrically driven over further electric motor means, wherein a further power engine is arranged to power supply said further electric motor means over a further electric generator. Hereby the mechanical drive transmission between the parts of the vehicle can be avoided.
It is preferred that also said further power engine and associated electric generator are arranged in the rear portion, since also this arrangement results in an advantage as regards installation and space.
The first power engine is preferably over a drive shaft and a transmission arranged, over a drive shaft, to mechanically drive the front wheel shaft, which carries the front wheel pair. Further, according to a second aspect, the first power engine is, over the drive shaft and the transmission, arranged to mechanically over a drive shaft drive the first wheel shaft in the rear portion, said first wheel shaft thus carrying the first wheel pair.
Suitably, the front wheel pair is arranged on a rigid front wheel axis and a first driven wheel pair on a rigid first wheel axis, wherein of said at least two driven wheel pairs on the rear portion, the first wheel pair being arranged closest to the steering joint being rigidly connected to the rear portion.
By the first wheel shaft being interconnected with a second shaft carrying the second driven wheel pair over a pendulum suspension device, a bogie arrangement is formed and good drivability on uneven surfaces obtained.
The vehicle according to the invention usually provides a driver's cabin but can also be remote controlled.
Through the invention, a high degree of modularity is made possible, which means that in a conventionally built articulated steering load-carrying vehicle having two wheel pairs, the ordinary engine and the ordinary driveline can be maintained. An auxiliary module being comprised of, as an example, in its simplest form, a unit including driving arrangements for the second wheel pair with appropriate adjustment parts can hereby be provided as required for increased capacity utilization in cases where this is desired. A vehicle wherein the second wheel pair is provided non driven, can thus afterwards be completed with drive arrangement for the upgrading of the vehicle if requirements for increased capacity and driving effect should occur.
Preferably the steering of the second wheel pair is formed as any one from the group: hydraulic slave control being regulated by an angle between the portions of the vehicle during turning; a mechanical control, wherein a link system detects an angling of the steering joint and transmits a rotational movement to the respective wheel of the second wheel pair; an electric control, wherein an angle detector in the steering joint is arranged to send signals to control members which are arranged to provide output signals to rotational actuators for the wheels.
The invention also concerns a system for driving in respect of an articulated steering load-carrying vehicle according to the above which has a controllable joint with a second wheel pair being arranged in a rear portion of the articulated steering load-carrying vehicle, wherein the system includes electric motor means for electric motor driving of the second wheel pair.
The system is preferably comprised of an auxiliary module for a conventionally constructed articulated steering load-carrying vehicle having two wheel pairs.
The system preferably includes a second power engine for power supply of said electric motor means over an electric generator.